The balance scales (a), (b) and (c) are known to be in equilibirum. How many circles should you put in place of the question mark so that the balance scale (d) is also in equilibrium? Justify your answer!

Zināms, ka svari (a), (b) un (c) atrodas līdzsvarā. Cik aplīšu jāliek jautājuma zīmes vietā, lai svari (d) atrastos līdzsvarā? Atbildi pamatot!